1. Field of the Invention
The present invention provides positive and negative directional digitally operated buffer amplifiers.
2. Description of the Prior Art
When load is connected to an analog signal (large-amplitude low-frequency alternating current) source that has no driving capability, it has been conventional to use a buffer amplifier between the signal source and the load so that the load will not affect signals. However, if the buffer amplifier consists of an operational amplifier in which MOS elements are used, offset voltage is generated due to the poor consistency of the MOS elements, thus causing errors to occur in the input signal source voltage and the output voltage.
The present invention provides digitally-operated analog buffer amplifiers which are characterized by small circuits, no offset voltage, high speed and low power consumption.
In accordance with the teachings of the present invention, circuit means are provided so that when the value of the output voltage of the buffer amplifier nears the approximate value (set voltage value) of the input voltage value, the input terminal and output terminal short-circuit so that the output voltage and the input voltage are made equal, thereby preventing the generation of offset voltage. Power consumption is reduced because the circuit completes the operation in a digital operation state.